Scotometer



July 29, 1930. H. M. ARMSTRONG 1,771,908

SCOTOMETER 6 Sheets-Sheet l Filed Nov. 1929 Q/NVVENTOR W7IKQZL W Z KM July 29, 1930. H. M. ARMSTRONG 1,771,903

SCOTOMETER Filed Nov'. 9, 1929 6 Sheets-Sheet 2 HTTORNEY III IV In h} M 2 I i l I II I H 1 H I ll 7% INVENTOR July 29, 1930. H. M. ARMSTRONG SCOTOMETER Filed Nov. 9, 1929 6 Sheets-Sheet 3 lA/VEA/TOR arm/ms) July429, 1930. H. M. ARMSTRONG SCOTOMETER 6 Sheets-Sheet 4 Filed Nov. 1929 Fig. 5.

lNl/E/VTOR HTTORIVEY Fig. 7.

July 29, 1930. H. M; ARMSTRONG SCOTOMETER 6 Sheets-Sheet 5 Filed Nov. 9, 1929 r A T TORNE) H. M. ARMSTRONG July 29, 1930.

SCOTOMETER Filed. Nov. 1929 6 Sheets-Sheet 6 /N VE N TOR ATTORNEY 2o nism therewith, and motion reducing mecha Opposite sides of'the' frai-ne 12' and thenover 7 30 Fig. 3 a side View.

- 45 spaced from, the panel 11. The panel 14 is is moved intoand outof operative position-by 95 lower part of the frame 12 or to the feet 13 carrier 30 secured" toithe-outer"facesofione- PatenteclJulyZQ, 1930 Q I V i i V UNITED stares Application filed November 9, 1929, Serial No. 405,990, and in Great Britain July 4, 1928;

This invention has relation to instruments and supported in an inclined position by a by which the relative and absolute blind areas strut or prop l6. Adjusta'bly mountedon the of the eyes of a person can be'mapped out and upper end of the framework 15' i's'a chin rest has relation to that type of instrun'lent known 17. f

' as a scotometer. g The Bjerrum screen has a fixed point or ,55

' A scotometer has been proposed in which a spot mounted in, a position such that'thefey-e' spotor object is formed or fitted so as to be of a person under examination can, fby adiresponsive to the movement of a magnet held justment of the chin rest 17, be'brou'ght exact} behind the test board or disc, the magnet bely opposite. 18 is the movable object} con yo ing combined with means for making a marl; sisting of a White-or colouredbead. "The ob 1'60 orprick at the desired places on or in a chart 'ject 18 is suspended infront' of the screen, secured on the back of the board or disc. the suspensory means comprising-two cords A scotometer, according to this invention, 19 or the like, each of wl'iich'isled to'a top comprises Bjerrum screen having a fixed front corner of the screen and then fiver a 15 point thereon, an object, for example, a white pulley 20" mounted'inthe "frame 12: The 05 or coloured bead, suspended in front of, and cords 1'9 extend-downtheopposite' sides ofthe movable in relation to, the screen recording frame 12 and-to theends are attached weights means disposed at the rear of the screen and 21. To the 'weijghts'21 other icords" 22f are 1 connected to the object to move in synchroalso attached. Thesecordsflfi are-ledupthe nism in the connection. 1 pulleys 23 mounted on'the' fi'ameIQ at' the In order that the invention, the object and top rear 'co'rners' thereof. The-pulleys 20, 2?) nature of which have been set forth, may be at. each corner are disp'osed sid'e' by sicle and particularly described and ascertained, refare, preferably, mounted on a} common spin" 1 25 erence will now be made to the constructional dle. The cords 22, after passing over-the embodiment of the invention illustrated in the pulleys 23' are led down behind the'screen accompanying drawings, in which and'are-connected' with a pantograph'fi lr-at Fig. l is a rear elevational View. I the point at which the-traceror stylus would Fig. 2 a front elevational view. ordinarily be positioned; 'I he-pantograph v 2a is pivotally'mountedonan upp'er and hori- .80 4 a Sectional iew on the line of ZO IltHl member Of the-frame and Fig. l. :point at which the tracer or'stylus-iwould or- Figs. 5, 6 and 7 are, respectively, elevaclin arily'be positioned'there =a= bracket-25 tional, side and plan views of the pantograph. W v111 fld rming an anchorage Figs. 8, 9 and 10 are, respectively, a secfor the cords 22,"constitutes a carrier-fora tional elevation, rear view and a plan ofthe handle 26 by which the-pantograp'h is' o'perhandle of the pantograph and the trigger by 'at'edand which may be integralwith which the pricker shown in rear View and in bracket 25i;"Onthe'handle.2'6 alever or trigsection in Figs. 11 and 12, respectively, is .ger 271s plvotallymountedandeonstit'utes 40 operated. I the operatingmeansof a Bowd enwiremech-a The Bjerrum screen comprises a panel 11 anism' 28-a nd which is-=led=tfo thep'arto'fthe mounted in a frame 12 supported in a verpantograph 24 on which the recordingmeans tical position by feet 13. 14 is a second panel is mounted. The rtec'ording nieans is conmounted in the frame 12 in front of, but ne'cted with-theB'o'wden wir'e-mec'l ianism a-nd mounted at the lower part of the panel 11, operation of tlie triggeror lever -27, The the part of which above thepanel 14 is covrecording means may comprisea pencil or, ered with black cloth. 15 is a framework and preferably,"asshown, a ricker oruiee'clile pivotally attached at its lower end to the 29. Thjelprick'er=or-needle 29 is; ln'ountdfin of the constituent members of the pantograph 24:, and is under the action of a spring 31, which tends to hold it in its inoperative position. The Bowden wire mechanism acts on the pricker or needle 29 through a lever 32 and a piston 33 contained in a cylinder 34: forming part of the carrier 30. The pricker or needle is mounted on the piston 33.

The cords 19, 22 are made of such length that the object 18 occupies a position in front of the screen that is coincidentwith point on the pantograph 24: at which the tracer or stylus would ordinarily be mounted.

' 35 is a frame to receive a chart or record sheet; the frame is mounted on the back of the screen and positioned opposite the area of movement of the pricker or needle 29.

, In use, thepatient is seated opposite the Bjerrum screen and is caused to rest his chin on the rest 17, which is then adjusted so to brin the eve under examination exactl' onu I L posite the fixed point. The ObJGCl) 18 is moved .in relation to the screen by the operator grasping the handle 26 and moving the pantograph 24. Each time the patient announces that the object 18 is out ofhis range of sight, the operator actuates the lever or trigger 27 and makes a record on the chart.

' I claim: v

1. A scotometer, comprising in, combination, a Bjerrum screen having a fixed view point indicated thereon, a movable object suspended in front of said screen, means for moving said object as desired, pantograph mechanism for reproducing the travel of the movable object, an operating handle adapted to control the movementot the said movable object, trigger mechanism mounted on said handle, recording means located in said pantograph, and a flexible transmission means between the trigger mechanism and said recording means substantially as described.

2. A scotometer, comprising in co1nbina- ,tion, a Bjerrum screen having a fixed View point indicated thereon, a movable object suspendedvin front of said screen, means for mov1ng said ob ect as ClBSH'GCl, pantograph mechanism for reproducing the travel of the movable object, an operating handle adapted to control the movement of the said movable object, trigger mechanism mounted on said handle, recording meanslocated in said pantograph, said means comprising a spring re turn pricker and flexible transmission means between said trigger mechanism and said spring return pricker substantially as described. a;

3. A. scotometer, comprising a combination of a B errum screen having fixed view point indicated thereon, a movable ob ect suspended in front of said screen, an operating handle adapted to control the movement of said movable object, wei ht loaded cords connecting said movable OlOJGCt and said handle, pantograph mechanismattached to said operating handle, trigger mechanism mounted on said handle, spring returned pricker mounted on said pantograph and flexible transmission means between said trigger mechanism and said pricker substantially as described.

i. A scotometer comprising in combination a Bjerrum screen having a fixed view point indicated thereon, a movable object suspended in front of said screen, an operating handleadapted to control the movement of said movable object, weight loaded cords connecting said object and said.operating handle, pantograph mechanism attached to said operating handle, trigger mechanism carried by said handle, spring returned recording pricker, a bell crank lever for operating said pricker and Bowden wire transmission between said trigger mechanism and said bell crank lever, substantially asdescribed.

In testimony whereof he has signed his name to this specification. 

